More museum trouble - this time in Philadelphia where staff at the Penn Museum are threatening strike action in a pay dispute.

Staff from visitor services, conservation and collections management among others have signaled their willingness to walk out if pay negotiations do not get anywhere, according to a report in Hyperallergic.

It comes after the Louvre in Paris was shut down for a day by a staff walkout, while security staff at London's Science Museum, Natural History Museum and V&A Museum all backed strike action with low pay and poor working conditions the common denominator in each case.

The number of paintings Black Sabbath singer Ozzy Osbourne has created in collaboration with a team of brush-wielding chimpanzees. The rocker painted the backgrounds before the primates daubed their designs on top to create works being auctioned to raise money for a chimpanzee sanctuary in Florida.

The former Librarian of Congress fired by President Trump has vowed to "strengthen the public knowledge ecosystem" in her new role with the largest philanthropic supporter of the arts in the United States.

Carla Hayden has joined the Andrew W. Mellon Foundation as a senior fellow whose duties will include advising on efforts to advance public knowledge through libraries and archives.

She was ousted by the White House after being accused of promoting "radical" literary material by a Trump-supporting campaign group.

The Acropolis closed to tourists on Tuesday afternoon as the Europe-wide heatwave brought temperatures of 38C (100.4F) to Athens.

It was shut by the Greek Culture Ministry's archaeological service after work restrictions were brought in to deal with rising temperatures.

The historical landmark is a UNESCO World Heritage Site and attracts around three million visitors a year.

Last week, the top of the Eiffel Tower was closed to visitors as a precaution when the temperature in Paris rose to almost 40C.

The organizers of a new exhibition in Italy say the 80 exhibits, from Andy Warhol to Giorgio De Chirico and Lucio Fontana, "allow visitors to trace the evolution of art" but more importantly they illustrate its use as illicit currency by organized crime.

The works on show at the Palazzo della Cultura in Reggio Calabria were all seized by the authorities from the country's mafia gangs.

Some were found after an investigation pinpointed an art gallery in Rome as a center for money laundering with others turning up after a raid of the offices of a video game rental business that was helping criminals evade tax.

1 - The "painter's village" of L'Estaque on the outskirts of Marseille has been devastated by wild fires. The blaze in the port, captured on canvas by Paul Cezanne and Georges Braque among others, has damaged dozens of homes and left more than 100 people injured.

2 - The founder of the African American Museum in Dallas, Harry Robinson, Jr., is stepping down after 50 years in charge and being replaced by Lisa Brown Ross. The museum has one of the largest collections of African American folk art in the United States.

3 - A paint-splattered armchair and artwork by Henri Matisse and Jasper Johns are among the lots being auctioned by Bonhams in the next sale of items from the personal collection of Dorothy and Roy Lichtenstein. The Matisse sketch, valued at around $60,000, is one of the top lots in the online auction that runs from July 20 for 10 days and is the latest of several sales of the couple's collection.

1 - Alvaro Barrington and Jade Fadojutimi are two of the eight abstract painters with work in a group show at London's Pippy Houldsworth Gallery. The show, which opens tonight, is called As the Earth Trembles and takes its name from a poem by American feminist writer Adrienne Rich.

2 - Another group show, another literary inspiration. This time it is the opening of Claudine's House at Ross + Kramer on New York's West 27th Street. The title comes from a novel by French writer Colette and features work by Anders Hamilton and Athena LaTocha among others.

3 - Eleven years worth of daily animal encounters in the streets of Queens inform Sam Cockrell's first solo show at New York's Blade Study on Pike Street. Cockrell has taken a daily digital image of a creature he meets near his home, from bugs to birds, then created a small airbrushed 8 by 10 inch canvas version.